An entire section of a high-rise apartment block has collapsed in the Russian southern city of Astrakhan following an explosion. Five people have been killed, five are still missing and 12 are injured.

­A total of 26 people have so far been rescued, according to an Emergency Ministry spokesman. Some of them were pulled out from under the rubble. Seven people were hospitalized, some with serious fractures and injuries. Rescuers continue to dig the rubble in hopes of finding survivors.

The explosion took place at around 2pm local time. Initially the three lower floors collapsed, followed by the entire section of the building.

YouTube user Vadim128777 uploaded a video showing the very moment when the whole block of apartments collapsed.

In the comment below, he wrote that a man who, at great personal risk, came to help an old woman who was calling for aid. “She was crying and calling for help,” the user wrote. The building collapsed when the man reached the woman.

“We could hardly have run away,” he said.

It remains unclear how many people were at home at the time of the explosion. According to the official, 258 people lived in the block, including 90 in the crumbled section of the building. Ten people have been given temporary accommodation in a local school.

The likeliest cause of the tragedy is an explosion of natural gas, the Investigative Committee said. It is believed that tenants on the third or fourth floors may have illegally renovated their apartments, damaging the pipes in the process. However, investigators do not rule out the possibility that a suicide attempt by one of the tenants could have caused a gas leak resulting in the blast.

One of the tenants "had earlier expressed an intention to take his life and made suicide attempts by opening gas burners," committee spokesman Vladimir Markin told Interfax.

A throughout investigation into the blast has been started. A team from the Emergency Situations Ministry has arrived in Astrakhan.

Russian Prime Minister Putin has ordered that the Astrakhan communal services officials who were in charge of controlling the gas network be suspended from their duties until the end of the investigation.